Epitaxial growth of p-sexiphenyl film on highly oriented pyrolytic graphite surface studied by scanning tunneling microscopy

The epitaxial growth of p-sexiphenyl (C₃₆H₂₆, 6P) on highly oriented pyrolytic graphite (HOPG) surface has been investigated by scanning tunneling microscopy (STM). 6P molecules prefer epitaxial growth with the long axis along the [110] direction (armchair direction) of the HOPG substrate, with the unit cell parameters b₁ = 0.67 ± 0.06 nm, b₂ = 5.97 ± 0.06 nm and angle of 88 ± 3° between them. The relation of the 6P overlayer lattice vectors with the HOPG substrate has also been deduced, i.e. the 5 × 1 supercell is in a point-on-point commensurate relation with respect to the HOPG substrate surface.